The 23rd Rocky Mountain Folks Festival, the third summer festival put on by the folks at Planet Bluegrass (after Telluride and RockyGrass), has always been more experimental in the artists it showcases than its more famous big brothers. This year’s festival brought in a little bit of everything, from country-tinged lonesome crooning to experimental indie pop to new-age Celtic and high-energy rock to Lyons from Friday to Sunday.

Looking at the lineup for this year’s festival, the headliners for each night, Celtic songstress Loreena McKennitt, high-energy rockers the John Butler Trio, and legendary singer-songwriter John Prine all jumped out. All but McKennitt had played Folks before.

It was also interesting to see some of the other names on the bill. For instance, Minnesota-based folk singer Ellis, who has come to the festival for years and usually plays a set to a packed house at the intimate Wildflower Pavilion, got a main stage slot this year, where she dazzled on “Coming Home to You.”

However, it was the more experimental acts that proved most interesting of the pre-dinner sets, such as Brookyln-based indie pop quintet Lucius on Friday, who had a mesmerizing upbeat stage presence and brilliant songs, including the title track from their full-length debut CD “Wildewoman” that comes out Oct. 15. Saturday brought Canadian 2000 National Poetry Slam Champion Shane Koyczan, who was backed by four musicians playing seemingly ambient, but in fact very structured songs as accompaniment to Koyczan’s stream-of-consciousness delivery. Keeping with the theme of exploring musical boundaries in the late afternoon, Sunday brought Charles Bradley and His Extraordinaires for a set of funk and soul that seemed straight from a ’70s time warp, right down to Bradley’s bright red suit and the covers of “Summer in the City” and “Heart of Gold.”

Of course, there were plenty of more familiar artists for those who wanted such. Friday brought former Men at Work frontman Colin Hay, who had a very wry, self-deprecating stage manner. He joked about how his friends told him the ’80s were becoming popular again and how he should be happy about it and about an encounter with Little Richard at an awards show in the ’80s that made him feel “very white.” Hay played several of his old hits, including “Who Can It Be Now” and “Down Under,” changing the latter’s arrangement to be more moody.

McKennitt closed Friday with a brilliant set, her amazing vocals showing no signs of stress from the altitude on the danceable “Santiago” or the haunting “Lady of Shalott,” a musical adaptation of an Alfred, Lord Tennyson, poem that cast a spell over the crowd.

Saturday brought Patty Griffin back to the Lyons stage, who told an anecdote about her last appearance at the festival under a driving rain and very cold weather, which, she said, is indicative of why Rocky Mountain Folks Festival is one of her favorite festivals because the audience stayed through those horrible conditions. Griffin mixed in arrangements of traditional songs like “Samson and Delilah” with songs from her new album “American Kid,” including the upbeat waltz “Get Ready Marie.”

Perhaps the highlight of the weekend was the John Butler Trio set, which brought the entire festival crowd to its feet to dance along on songs like “Better Than” and “One Way Road.” Butler, who has been headlining shows to rock-type audiences, joked early in his set about how the dancers seemed to be off to the side while the main festival crowd was sitting down, but by the halfway point of the set, everyone was on their feet. Butler also showcased his brilliant guitar playing on his 11-string guitar on the captivating “Ocean” and the haunting “Losing You.”

Sunday featured sets from Denver local Nathaniel Rateliff, whose passionate delivery won over the early afternoon crowd, as well as Canadian singer-songwriter Ariana Gillis (the fourth Canadian performer of the weekend), whose social conscious songwriting was best exemplified on “The Cove,” a song written about an annual dolphin slaughter on YouTube.

The festival closed with the new and the old representing different approaches to songwriting. First up was Colin Meloy of the Decemberists, playing an intimate set that included a tender “Hazards of Love,” a brilliant “Down by the Water,” and the quirky “Calamity Song.” When Meloy muffed a riff at the end of the latter, he gave the crowd a bemused smile.

John Prine, whose work has been covered by many different artists, including Bonnie Raitt and John Denver, closed the festival. Prine, who played at the Paramount in May, was in no better vocal form this time. Right out of the gate, his voice sounded very rough and gravely, far more than on his recordings. His songs however, stand the test, and he mixed in many of his best-loved tunes, including “Picture Show” and “Your Flag Decal Won’t Get You Into Heaven Anymore.”